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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 21 January 2011 by dana1981

the IPCC’s current thinking is that up to 2° of warming compared with the present would be harmless and even beneficial. Since far greater temperatures than this have been the rule on Earth for most of the past 600 million years, there is no sound scientific basis for the assumption that “significant environmental and economic damage” would result from so small an additional warming. However, significant economic damage is already resulting from the costly but pointlessly Canute-like attempts governments to try to make “global warming” go away.

Chris, I Have a Feeling We're Not in the Paleozoic Anymore

Monckton's reference to the past 600 million years is simply not relevant, because millions of years ago ecosystems and the species living in them were radically different from those today. We cannot infer the amount of environmental and economic damage we will experience based on the state of the climate 600 million years ago.

What Does the IPCC Say?

Monckton's statement that the IPCC concluded that up to 2°C warming compared to the present would be harmless or beneficial is simply false. Here is the actual IPCC conclusion on the subject.

Limited and early analytical results from integrated analyses of the costs and benefits of mitigation indicate that they are broadly comparable in magnitude, but do not as yet permit an unambiguous determination of an emissions pathway or stabilisation level where benefits exceed costs.

There have been numerous studies pertaining to ecological and economic costs and benefits of additional global warming since the IPCC Fourth Assessment Report, (AR4) and these will be the subject of a future Monckton Myth. However, Monckton is incorrect that the IPCC has concluded that up to 2°C warming from current levels will be harmless or beneficial - the IPCC did not quantify a specific level at which climate change damages exceed the benefits. The IPCC did conclude that this level of warming will have some serious negative impacts:

Approximately 20 to 30% of plant and animal species assessed so far (in an unbiased sample) are likely to be at increasingly high risk of extinction as global mean temperatures exceed a warming of 2 to 3°C above preindustrial levels (medium confidence).

As you can see, there are numerous adverse risks to ecosystems for a warming of 2-3°C above pre-industrial levels. Of course, impacts to ecosystems are only one piece of the puzzle when trying to determine when the negatives will outweigh the positives. In chapter 5 of WG II, the IPCC concludes that for a small amount of warming, crop yields may increase slightly in mid- and high-latitude regions, but will decrease in low-latitude regions (especially the tropics), increasing the risk of hunger.

In short, the IPCC concludes that small amounts of warming will be a mixed bag, and contrary to Monckton's claims, does not set a level at which the net effects of warming will switch from beneficial to detrimental. However, Stetekee is correct that other groups have set 2°C of warming above pre-industrial levels as the danger limit.

The 2°C Danger Limit

The history of and reasoning behind the 2°C danger limit is discussed in a paper by Carlo and Julia Jaeger (2010). As they discuss, the limit was first suggested by Yale economist William Nordhaus in 1975, who made the following argument:

As a first approximation, it seems reasonable to argue that the climatic effects of carbon dioxide should be kept within the normal range of long-term climatic variation. According to most sources the range of variation between distinct climatic regimes is in the order of ±5°C, and at the present time the global climate is at the high end of this range. If there were global temperatures more than 2° or 3° above the current average temperature, this would take the climate outside of the range of observations which have been made over the last several hundred thousand years.

The same 2°C target was taken up by the WMO/ICSU/UNEP Advisory Group on Greenhouse Gases in 1990, which argued that a 2°C increase was ‘‘an upper limit beyond which the risks of grave damage to ecosystems, and of nonlinear responses, are expected to increase rapidly.’’ In 1995, the German Advisory Council on Global Change supported both of these lines of thinking. It considered the late Quaternary, (the period of the last 800,000 years), and claimed:

This geological epoch has shaped our present-day environment, with the lowest temperatures occurring in the last ice age (mean minimum around 10.4°C) and the highest temperatures during the last interglacial period (mean maximum around 16.1°C). If this temperature range is exceeded in either direction, dramatic changes in the composition and function of today’s ecosystems can be expected. If we extend the tolerance range by a further 0.5°C at either end, then the tolerable temperature window extends from 9.9 to 16.6°C. Today’s global mean temperature is around 15.3°C, which means that the temperature span to the tolerable maximum is currently only 1.3°C [2°C above pre-industrial levels].’’

Above 2°C the risks increase very substantially involving potentially large extinctions or even ecosystem collapses, major increases in hunger and water shortage risks as well as socio-economic damages, particularly in developing countries.

An Even Lower Long-Term Target

Hansen et al. (2008) argue that in the long-term, we should aim for an even lower atmospheric greenhouse gas concentration than would result in 2°C of surface warming.

We use paleoclimate data to show that long-term climate has high sensitivity to climate forcings and that the present global mean CO2, 385 ppm, is already in the dangerous zone....Equilibrium sea level rise for today’s 385 ppm CO2 is at least several meters, judging from paleoclimate history....If the present overshoot of this target CO2 [350 ppm, or approximately 1°C above pre-industrial levels] is not brief, there is a possibility of seeding irreversible catastrophic effects.

Danger, Chris Monckton, Danger!

As discussed above, although the IPCC has not established a specific warming target, there is a scientific case to be made for considering 2°C above pre-industrial levels (approximately 1°C above current levels) the 'danger limit' beyond which the risks of significant adverse impacts become too high.

In a later Monckton Myth, we will examine his assertion that the costs of reducing greenhouse gas emissions exceed the costs of adapting to climate change.

Comments

I get quite uncomfortable when I see sentences and paragraphs lifted from popular articles and argued against at a different level. Most of the atmospheric scientists I am familiar with say that water is the main greenhouse gas and that carbon dioxide is mainly coming from the sea in response to slightly warmer temperatures. Prof Lindzen who with respect knows far more about the atmosphere than I suspect you or I will ever do points out that it is what happens at a local level rather than a global level that really matters. His comments on carbon credits are worth a read if only to see what has been going on behind the scenes. Read his paper on my site http://billpeddie.wordpress.com and make up your own mind.

Nicely illustrates the point I keep trying to drive home with people. That being the fact that no one can state with any certainty just how far we can push the planet before the situation gets out of hand (not that it already isn't). I simply can't fathom why the human race is always so prepared to play Russian Roulette with the planet. The real danger is that should it get out of hand, decisions are likely to be made that could propel us into an even worse geo-engineering experiment than the one that was undertaken in the Industrial Revolution and has persisted until present day. The whole thing keeps reminding me of that old adage about "biting the hand that feeds you". Sooner or later it's going to bite back very hard.

Bill Peddie:
Most of the atmospheric scientists I am familiar with say that water is the main greenhouse gas and that carbon dioxide is mainly coming from the sea in response to slightly warmer temperatures.
Names and cites, please.

Bill, your post is largely off topic. I will not address your misguided ideas about the source of CO2 and water vapor. I'm pretty sure that Lindzen would disagree with you on both counts though.
Regarding Lindzen's intriguing stance on regional temperatures , which is more or less on topic-- I cannot be sure exactly what you or he are trying to convey in opposition to global warming by mentioning that. Of course regional temperatures are important. Scientists also know that there is large regional variability in annual temperatures, and that this inter-annual and intra-annual variability increases as the time window and area decrease.
Let me demonstrate the importance of regional variability, and what a warming of + 2 K in the mean annual global might mean. Here is the annual global surface temperature anomaly map for 2010 when the global anomaly was +0.63 K with respect to the 1951-1908 baseline:
Note the marked regional variability. Now what did this seemingly trivial (to some) warming mean for the people who live in and around Moscow this past summer when they experienced an unprecedented heat wave in late July and early August that killed many thousands of people? Here are the monthly, seasonal and annual temperature anomalies for Moscow from GISTEMP (again with respect to the 51-80 baseline:
July: +7.8 K
August: +5.2 K
JJA (Boreal summer): +5.0 K
Annual (2010): +2.0 K
So in a year when the mean annual global temperature was +0.63 K, Moscow experienced a summer with mean temperatures +5 K above average, with a mean annual temperature anomaly of +2 K.
A mean annual temperature anomaly of 2 K for a given location is not trivial, and as shown above doesn't mean that each and every day was only 2K warmer than average.
What I am driving at here, and what Lindzen also knows, is that increasing the planet's mean annual temperature by +2 K will manifest itself as much greater warming at regional and seasonal scales. The reason being is that the warming shifts the probability distribution function of temperature to the right, which means that the tails (extremes) in temperature are increased. It is these extremes in temperature (and precipitation), which have already been detected and which will continue to increase in frequency and magnitude, that will pose huge problems for society in the future. And that is before we have even begun to address the negative impacts rising global ocean levels and ocean acidification.
Global warming doesn't mean that the whole planet will warm uniformly, scientists know that. They predicted many years ago that the northern high latitudes would warm much faster than other portions of the planet. We are indeed witnessing that. For example, Arctic amplification has resulted in the Arctic recently warming about 3 times faster than the the planet as a whole. And that has worrisome consequences in terms of positive feedbacks.

The answer mentions but doesn't highlight the fact that Monckton also confuses matters by speaking of 2ºC from the present, whereas the IPCC refers to 2ºC from pre-industrial times (about 1ºC above present).

Thanks Byron. I was going to make that point, but Steketee referenced 2-3°C from pre-industrial, and Monckton referenced 2°C from present, which is within Steketee's range.
Sometimes we refer to temps in relation to pre-industrial, and sometimes from current temps. Even the IPCC uses both, as mentioned in the article. So Monckton's use of current temps as the reference point isn't really a big deal.

So ... use of current temps as the reference point isn't really a big deal.

I kind of disagree. Temps are changing so fast, what is "current temps?" 1979? 1985? 2000? 2010?
I recently got annoyed because Spencer found a perfectly good reason to change his baseline from one range to another.

... we have just switched from a 20 year base period (1979 – 1998) to a more traditional 30 year base period (1981-2010) like that NOAA uses for climate “normals”.

I was already annoyed with his usual graph, because he hadn't set his baseline to 1979, when the satellite record began, but rather to the average from '79 to '98, which means something equivalent to roughly 1990, which conveniently, visually skips over a full decade of warming.
It doesn't help that he uses other tricks, like a Y axis scale that minimizes the variations, and a thick blue line that further blurs things.
Today, skeptics and scientists alike are generating many graphs with a baseline set to the midpoint (average) of the range of available measurements (1979-2010 for satellite, for example).
But the instinctive reaction of most people is to view zero as normal. Setting zero to the period average, but moving one end point of that average, effectively keeps raising the base temperature, and ignoring all warming prior to that point.
In my mind, I always consider warming relative to 1979, which appears to be the point at which warming kicked in and aerosol dampening turned off. It appears to be close to what should be the "natural" temperature of the planet at this point in time were it not for elevated CO2 in the atmosphere.
But my point is that "current" is always a relative term, and it needs to be nailed down whenever anyone says anything. It needs to be stated clearly. 2˚C over today's temperatures (since we've already warmed about 0.9˚C) is pretty dangerously dang hot.

Well I have done as the moderator suggested and gone to the article which shows why Carbon Dioxide is more important than water as a Greenhouse gas. The article says:
"The other factor to consider is that water is evaporated from the land and sea and falls as rain or snow all the time. Thus the amount held in the atmosphere as water vapour varies greatly in just hours and days as result of the prevailing weather in any location. So even though water vapour is the greatest greenhouse gas, it is relatively short-lived. On the other hand, CO2 is removed from the air by natural geological-scale processes and these take a long time to work. Consequently CO2 stays in our atmosphere for years and even centuries. A small additional amount has a much more long-term effect."
Surely this is a very elementary error. The water and the carbon dixide does not hold onto the energy it absorbs, it loses it in collisions which occur usually within microseconds. It therefore only matters what the concentration of water molecules is at any one instant - not how long it stays in the atmosphere. The reason why water absorbs the Sun much better is because its bonding enables it to absorb at many points of the spectrum whereas carbon dioxide with its different architecture and bonding only has three major absorbtion peaks in the appropriate spectrum region.
I would stress there is still a great deal I dont understand but I would suggest that elementary stuff gets fixed in your replies.

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Moderator Response: Thanks for reading that post. You also need to put comments about that post on that thread rather than this one.

Great piece.
I also want to stress something Ron brought up above -- the inherent uncertainty in our proclamations of what is and isn't a "safe" or "acceptable" level of warming. I've been harping for quite some time that the 2C guardrail is much older than most people realize, which means it was chosen before all of the climate science discoveries of the last few decades, discoveries that heavily imply a lower "safe" limit than 2C.
The oldest reference I know of to 2C came in a UN-sponsored study involving a 15-member committee from 58 countries that was published in 1972(!), called Only One Earth. The graf I quoted on my site from that book:
----------------------------------
Clearly man has had nothing to do with these vast climatic changes [moving in and out of ice ages] in the past. And from the scale of the energy systems involved, it would seem rational to suppose that he is not likely to affect them in the future. But here we encounter another fact about our planetary life: the fragility of the balances through which the natural world that we know survives. In the field of climate, the sun’s radiations, the earth’s emissions, the universal influence of the oceans, and the impact of the ice are unquestionably vast and beyond any direct influence on the part of man. But the balance between incoming and outgoing radiation, the interplay of forces which preserves the average global level of temperature appear to be so even, so precise, that only the slightest shift in the energy balance could disrupt the whole system. It takes only the smallest movement at its fulcrum to swing a seesaw out of the horizontal. It may require only a very small percentage of change in the planet’s balance of energy to modify average temperatures by 2°C. Downward, this is another ice age; upward, a return to an ice-free age. In either case, the effects are global and catastrophic.
----------------------------------
Seems like at least some people had figured out nearly 40 years ago that 2C of warming wasn't such a terrific idea.

Bill,
At the risk of sounding naive/ignorant, the best comparison I would be able to offer is that a thinner blanket that is covering me 100% of the time will keep me warmer (or have as great a warming effect on me) as a thicker blanket that is constantly removed...assuming the analogy holds, I fail to see the fundamental error.

Bill Peddie:
Surely this is a very elementary error.
You seem to be misunderstanding the article. The basic point is that CO2 causes warming, which increases water vapor, which contributes to warming. The distinction between residence times -- at least as I understand it -- is basically the distinction between a forcing and a feedback.
Could you make your objection a little clearer?
I would stress there is still a great deal I dont understand
If you really believe this, then it would be reasonable for you to assume that it's you who's making an elementary error. Did you read the linked article on residence time, by any chance?

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Moderator Response: Despite Bill Peddie continuing the discussion on this thread, will everybody responding to him please do so on the water vapor thread?

The main problem here is the speed of warming. Even a very fast natural warming like the PETM could be measured in thousands, or tens of thoudands of years. Now we're talking about the possibility of a 6ºC warming in a century or two. That's even faster than some animal species can travel to catch up with it, let alone adapt.
The Triassic may have been hot, but it did not happen overnight. We will not have T-rexes here in 2 centuries, just because the temperature is roughly the same. The ecological consequences will be dire.
Likewise, our economy has evolved in this stable climate we've had since the Holocene began. Claiming that we can just shuffle it and it will turn out to be something better in the end is just wishful thinking.
Weather extremes are usually not economically benign. We already have anedoctal reports of rainy seasons in Africa becoming shorter and nastier. The late rain does damage when it's not there in the early season, and does damage again when it comes, in a monsoon-like fashion.
Calling this "beneficial" just because we had big dinosaurs at that temp hundreds of millions of years ago is just irresponsible.

Bill, the atmosphere can only hold a certain amount of water vapor. If the atmosphere gets hotter, it can hold more. But no matter how much water vapor we emit, the atmosphere will not be able to hold any more (unless it warms). Because of the short residence time of water vapor in the atmosphere, even if we emit a large quantity, it will just precipitate out of the atmosphere quickly. Thus it can't cause global warming.
However, if some other factor warms the atmosphere (like an increasing greenhouse effect), then the atmposphere can hold more water vapor, which in turn will increase the greenhouse effect further and cause additional warming. This is why water vapor is referred to as a feedback. It doesn't cause global warming, it only amplifies it.

Thank you for the article!
You could add, that its the speed of climate change what really matters. Perhaps a warmer climate has advantages for species, but the rate of change is too high that they can adapt. I think thats the main point and Monckton fails to see that.

The focus of this article is on temperature changes (global and local) caused by climate change, and on the deniers attitude of "Oh, 2°C isn't that bad - it is even good".
While we know these temperature changes can directly cause great "economic damage" (eg: Moscow's summer), they pale into comparison with the secondary effects: greater storm and rainfall intensity leading to flooding, and in the future rising sea levels leading to flooding of the world's major cities (Brisbane is facing another king tide today).
So while the man in the street might think "2°C isn't that bad - it will make winter nicer", his attitude may well change when you (or rather his insurance company) explain the secondary consequences of that change.

OT
I was organising my climate change links and I found (again) this jewel of a lecture series.
"Global Warming: Understanding the Forecast" by David Archer
http://geoflop.uchicago.edu/forecast/docs/lectures.html
I thought it might deserve a link from this site, possibly under Resources, but neither site is mine; so, leaving it to you to decide.
From what I sampled it contains much of the same material as his book, but I read the book and haven't watched the whole series.

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Response: Thanks for the URL. Have added it to the Resources page. All the videos are in mp4 format too - very convenient for me to download straight onto my iPad for easy viewing.

It is shocking that a British citizen would so mangle the history of King Canute. Perhaps the first British king - ruling about a thousand years ago. He is the one who is pictured as commanding the tides not to rise.
King Canute did this purely as a show to instruct his minions not to expect a king to perform miracles or stand in the way of nature. Pretty wise for a leader - even now.
Monkton has it completely wrong on that point. Not sure I can read much more of him after that.

"We cannot infer the amount of environmental and economic damage we will experience based on the state of the climate 600 million years ago. "
Then how do you justify using climate changes in the past to model what is happening/will happen in the next 100 years? In other words, the IPCC does exactly what you say Monckton is doing, but you say he cant do it, but the IPCC can. Double standards.
Your starting time point ('pre industrial levels') about which 'safe T' is assumed, is the coldest point in the last 10,000 years to make the assumption of what is 'safe' 'average T'. How convenient. The climate has been higher than pre industrial levels (ie Little Ice Age) for much of the Holocene, no adverse effects. Any scientists can show that these estimates of what is safe and what isnt choosing as a starting point the coldest period in the last 10,000 years, are ludicrous.

#22: The models the IPCC uses are based on the physics of the atmosphere and scenarios of emissions, combined with constraints established from palaeoclimate and supported by further physics. Monckton uses... the climate of the Earth before multicellular life was widespread (even before the Ediacaran fauna), when the Sun was sugnificantly fainter, the composition of the atmosphere was different, and the continents were in a completely different configuration. That's a great analogy with which to gamble the stability of agriculture and modern human life isn't it?
This year we've seen ruined harvests due to flood in Pakistan (and Queensland), and due to heat/drought in Russia, with the latter responsible for a record and ongoing spike in the FAO food price index. And given how much higher sea levels were in the last few million years with temperatures just a degree or two warmer, it's safe to say that significant sea level rise is very likely. I forget off the top of my head the proportion of human population that live within 5m of sea level or has marginal food security...

(O/T) rpauli #21: Canute was not a British king, but was king of England (but a Danish prince), who then unified the Danish and English crowns and subsequently claimed the Norwegian one. Don't think he ever ruled north of the border, where Malcolm II was in charge of the early Scottish kingdom. You're dead right about the wiseness of his actions though - commonly misinterpreted to this day!

"We cannot infer the amount of environmental and economic damage we will experience based on the state of the climate 600 million years ago. "
Then how do you justify using climate changes in the past to model what is happening/will happen in the next 100 years?

Probably because 600 million years ago there were no economic damages due to climate change because humans hadn't evolved yet.
While some of us hope that, despite the denialism-driven obstacles to action, that humans will still exist 100 years ago.
If you can't understand the fact that climate change today, when humans exist, will have more impact on humans than climate change 600 million years ago, when humans didn't exist, did ... Lord help us.

#22 thingadonta:
Like dhogaza said. We can use climate changes in the past to model what might happen physically, but we can't directly model economically because there was no human economy back then.
So we can estimate things like how high sea levels or temperatures will rise. You can't say that 'well, GDP damage back then was 0 so it will be 0 now', that's stupid.
You can estimate future damages based on knowing what the economy is like today and the damages you can expect (which you calculate from observations, models and palaeoclimate data).
Imagine we had an meteor coming to hit us. Monckton would tell us not to worry, over the Earth's history meteor strikes are the norm rather than the rule. 65 million years ago when a meteor hit us, economic losses were 0%!
But a scientist would use the impact evidence from 65 million years ago to work out what would happen today.

I am thinking what a poor argument Monckton makes when he say,
"Since far greater temperatures than this have been the rule on Earth for most of the past 600 million years, there is no sound scientific basis for the assumption that “significant environmental and economic damage” would result from so small an additional warming. "
Six hundred million years! Think how epically different Earth was then compared to now, it is just not comparable. From eye balling some graphs for temperature over the last millions of years, 2C warming from pre-industrial times seems to be the upper bound for interglacials over the last 500 thousand years. It is not till about 3 million years ago that it was that warm for any length of (geological) time. Our species has existed only since then!
How can Monckton put human civilisation at such risk?

Why did Monckton stop at the "past 600 million years" ? Surely he would have achieved a far more dramatic effect by stating "Since far greater temperatures than this have been the rule on Earth for most of the past four and a half billion years..." ?
Or is it something to do with not wanting to upset his Creationist followers by saying the Earth is too old ?

Well, a 2 degree increase temperature change is very important for the corn growers of America. From the farmers, I understand that most of the entire corn crop of the U.S. would be lost. Too hot to pollinate. We would then be buying most of the corn from the Canadians.

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